Field of the Invention
The invention relates to a method of operating a rotary printing press with at least two printing forms. The printing forms are imageable in the printing press and allow a number of prints to be made after a single imaging. The invention further relates to a device for carrying out the process.
Published German patent application DE 195 12 420 A1 discloses a multi-color printing press with an imaging unit that can be assigned successively to a plurality of printing-form cylinders. This reduces costs in comparison with a system in which a separate imaging apparatus is assigned to each printing-form cylinder. No provisions are made for an imaging of printing forms during the operation of the printing press. As a consequence the operation must be interrupted for each new print job. The resulting waste paper when operation is resumed, combined with the high total of downtimes, causes a comparatively poor economic efficiency.
German patent DE-PS 28 44 418 describes a web-fed rotary printing press with a flying change of the printing image in an imprinting unit. When a defined number of copies have been printed with a first imprinting image, the presently operating printing unit is shut down and a further printing unit of the imprinting unit is put into operation without stopping the press. While the further printing unit is in operation, the shut-down printing unit can be prepared for the next imprint. No provision is made for an imaging of printing forms in the printing press. As a consequence, in the case of small numbers of copies per printed image, the pre-press costs, e.g. the photochemical plate exposure, constitute a comparatively large proportion of the total costs. An automated change of the printing plates can be accomplished only with considerable technical effort.